<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>simple</title>
    <link rel="stylesheet" href="./css/bootstrap.css" />
    <script src="./js/bootstrap.js"></script>
    <link rel="stylesheet" href="./css/bs-slide.css">
    </link>
</head>

<body>
    <!-- toggle 切换器 -->
    <button class="btn btn-info" data-bs-toggle="collapse" data-bs-target="#ssss">
        xxx
    </button>
    <!-- 内容 隐藏或出现 -->
    <div class="collapse" id="ssss">
        <ul class="ty-list">
            <li>内容一</li>
            <li>内容二</li>
            <li>内容三</li>
        </ul>
    </div>
</body>

</html>